Acetylene (C2H2) and benzene (C6H6) have the same empirical formula. In fact, benzene can be made from acetylene as follows: 3C2H2(g) → C6H6(l) The enthalpies of combustion for C2H2 and C6H6 are −1299.4 kJ/mol and −3267.4 kJ/mol, respectively. Calculate the standard enthalpies of formation of C2H2 and C6H6. Assume that the products of the combustions are CO2(g) and H2O(l).

definition

                    entropy is a measure of the randomness or the extent of disorder of a chemical process.

                      enthalpy is a measure of the heat change of a reaction occurring at a constant pressure.

measurement units:

                        entropy is measured in joule per kelvin (jk⁻¹)   whereas enthalpy is measured in joule per mole (jmol⁻¹)

requirements:

                            entropy has no requirements or limits, and its change is measured by the division between the heat change of the chemical process and the temperature.

                              in contrast, enthalpy can only be related to the heat change of the reaction under standard conditions.